As the sizes of color picture tubes have increased, there has been a corresponding increase in the sizes and weights of tube components. One of these components is the shadow mask frame. Present color picture tubes use steel frames to support the shadow masks within the faceplate panels of the tubes. One type of frame is made from a continuous piece of L-shaped steel, that is bent and welded to itself at its ends. Another type of frame is formed by pressing a flat steel sheet into the shape of the frame. A third type of frame is disclosed in Canadian Patent 988,141, issued to T. M. Shrader and K. A. Long on Apr. 27, 1976. This patent shows a frame that is formed from four pieces that are welded together at the four corners of the frame. The cited purpose of using four pieces is to provide an adjustable frame to precisely fit within a particular mask. Each of the four pieces has two flanges configured in an L-shaped cross-section. A first of the flanges extends toward a screen of the tube and a second flange extends from the first flange toward a central longitudinal axis of the tube. In each piece, the first flange extends beyond the second flange at both ends of the piece. These extensions of the first flange overlap each other in the corners of the frame and are where the pieces are welded together.
The three frame types discussed above are usually supported within a faceplate panel by either three or four springs that are attached to the sides of the frames. Recently, large tubes have been suggested that are supported within faceplates by four springs located at the corners of the mask frame. The present invention provides a frame with reduced weight that can be used in a tube having corner support springs.